Summary of Work: The tyrosine kinase inhibitor AG 556 reduces serum tumor necrosis factor (TNF) levels and tissue injury and improves survival in both small and large animal models of gram-negative infection and sepsis. No data is presently available regarding the effects of AG 556 during gram-positive infection. We therefore investigated this agent in rats challenged with Staphylococcus aureus. In these studies we found that AG 556 was not beneficial with gram- positive infection. We have continued these studies to determine whether AG 556 would be beneficial during gram-positive infection in a canine model of peritonitis which utilizes antibiotics and fluid support. In a similar model, we had shown that AG 556 clearly improved survival with gram-negative infection.